Among heat exchangers used in air conditioners and the like, a cross fin type is known, as shown in FIG. 1. FIG. 1 is a schematic perspective view that depicts a heat exchanger 101 as one example of a cross fin type heat exchanger.
The heat exchanger 101 comprises a plurality of plate fins 11 disposed in parallel at a prescribed interval, a plurality of heat transfer pipes 12 that pass through the plurality of plate fins 11 in the plate thickness direction, a plurality of U-shaped pipes 31, each U-shaped pipe 31 connecting the pipe end parts 12a of a pair of heat transfer pipes 12, a header pipe 32 that connects the pipe end parts 12a of the plurality of heat transfer pipes 12, and a plurality of capillary tubes 41 that branches from a distributor 33 and that is connected to the pipe end parts 12a of the heat transfer pipes 12.
The plurality of heat transfer pipes 12 passes through the plurality of plate fins 11 in the plate thickness direction, and each heat transfer pipe 12 is then expanded across its entire length (hereinafter, referred to as the primary flare fabrication) and joined to the plate fins 11. Furthermore, the pipe end part 12a of each heat transfer pipe 12 is further expanded in two stages (hereinafter, referred to as the secondary and tertiary flare fabrication) to form a large-diameter cylindrical flared part 14 and a tapered auxiliary flared part 15 on the pipe end face side of the flared part 14 (refer to FIG. 2). The U-shaped pipes 31, the header pipe 32, and the capillary tubes 41 are brazed to the flared part 14 formed in each pipe end part 12a. 
Next, the conventional method of connecting and connection structure of the heat transfer pipe 12 and the capillary tubes 41 will be explained using FIG. 2 through FIG. 7. FIG. 2 is a cross-sectional view (before flat crushing) that depicts the flat crushing fabrication of the flared part 14, wherein a pinching unit 161 is employed. FIG. 3 is a cross-sectional view taken along the A—A line in FIG. 2. FIG. 4 is a cross-sectional view (after flat crushing) that depicts the flat crushing fabrication of the flared part 14, wherein the pinching unit 161 is employed. FIG. 5 is a cross-sectional view taken along the A—A line in FIG. 4. FIG. 6 is a view (a partially broken view) of the connection structure between the heat transfer pipe 12 and the capillary tube 41 as seen from the flat crushing direction of the flared part 14. FIG. 7 is a view (a partially broken view) from the B arrow direction in FIG. 6.
First, flat crushing fabrication is performed on the flared part 14 of the heat transfer pipe 12 in the pipe latitudinal direction to form a pinched part 114a, wherein a tube end part 41a of the capillary tube 41 is inserted.
Herein, the pinching unit 161 used in the flat crushing fabrication has a pair of levers 162, and the tip parts thereof are capable of mutually breaking away and drawing near. The opposing surface of the tip part of each lever 162 is provided with a U-shaped groove 162a. In addition, a pin 163 is provided between the tip parts of the pair of levers 162. The pin 163 comprises a plate-shaped retaining part 163a, and a columnar part 163b provided on the tip face of the retaining part 163a. The columnar part 163b is disposed between the U-shaped grooves 162a of the pair of levers 162, and is the part that, by being interposed between the pair of levers 162 in the lateral direction, forms a pinched part 114a of a tubular part 114b (refer to FIG. 4 and FIG. 5), having a space wherein the tube end part 41a of the capillary tube 41 is inserted.
Furthermore, as shown in FIG. 2 and FIG. 3, the pipe end part 12a of the heat transfer pipe 12, wherein the capillary tube 41 is connected, is inserted between the tip parts of the pair of levers 162 of the pinching unit 161, and the end face of the pipe end part 12a is brought into contact with the tip face of the retaining part 163a. Thereby, the columnar part 163b is inserted in the pipe end part 12a. 
Next, the tip parts of the pair of levers 162 are closed. Upon doing so, as shown in FIG. 4 and FIG. 5, the tubular part 114b, having a space wherein the tube end part 41a of the capillary tube 41 is inserted, remains, the substantial entirety of the flared part 114 is flatly crushed in the pipe latitudinal direction, thus forming the pinched part 114a. The pinched part 114a has a tubular part 114b having a space wherein the tube end part 41a of the capillary tube 41 is inserted, and a flat flatly crushed sealed part 114c formed on both sides of the tubular part 114b. 
Next, as shown in FIG. 6 and FIG. 7, the tube end part 41a of the capillary tube 41 is inserted in the tubular part 114b of the pipe end part 12a of the heat transfer pipe 12. Further, the tube end part 41a of the capillary tube 41 and the tubular part 114b are brazed. To seal the pipe end part 12a of the heat transfer pipe 12, the flatly crushed sealed part 114c is brazed.
Thus, the heat transfer pipe 12 and the capillary tube 41 having a diameter smaller than the heat transfer pipe 12 are connected by direct brazing (e.g., refer to Patent Document 1).
Patent Document 1
Japanese Published Patent Application No. HEI 6-307736